Field
Embodiments disclosed herein generally relate to methods for deposition of a film. More specifically, embodiments an apparatus and methods of depositing a nanocrystalline diamond film for use in semiconductor devices.
Description of the Related Art
As the semiconductor industry introduces new generations of integrated circuits (IC's) having higher performance and greater functionality, the density of the elements that form those IC's is increased, while the dimensions, size and spacing between the individual components or elements are reduced. While in the past such reductions were limited only by the ability to define the structures using photolithography, device geometries having dimensions measured in micrometers (μm) or nanometers (nm) have created new limiting factors, such as the conductivity of the conductive interconnects, the dielectric constant of the insulating material(s) used between the interconnects, etching the small structures or other challenges in 3D NAND or DRAM form processes. These limitations may be benefited by more durable, higher thermal conductivity and higher hardness hardmasks.
A thick carbon hardmask is well known and commonly used as POR film. However, current graphitic, Sp2 type or other carbon hardmask compositions are expected to be insufficient as DRAM and NAND continue their scaling down to under ˜10 nm regime. This downscaling will require even higher aspect ratio deep contact hole or trench etch. The high aspect ratio etch issues include clogging, hole-shape distortion, and pattern deformation, top critical dimension blow up, line bending, profile bowing are generally observed in these applications. Many etch challenges are dependent on the hardmask material property. Deep contact hole deformation can be related to lower hardmask density and poor thermal conductivity. Slit pattern deformation or line bending is due to hardmask material lower selectivity and stress. Therefore, it is desirable to have an etch hardmask with higher density, higher etch selectivity, lower stress and excellent thermal conductivity.
Diamond and diamond like materials are known as high hardness materials. Due to their high hardness, surface inertness, and low friction coefficient, synthetic diamond materials have been applied as a protective coating and in microelectromechanical systems (MEMS) among other uses. Diamond films, such as nanocrystalline diamond (NCD), have been synthesized by hot filament CVD and microwave CVD. However, there are a variety of difficulties with the use of hot filament CVD and microwave CVD processes to form nanocrystalline diamond films.
In hot filament CVD, a metal filament is used to activate the precursor gases for deposition. As expected, the metal filament is exposed to the precursor gases during the film forming process. As a result, precursor gases can react with the metal filament leading to metal contamination issues in the final product. Compared to hot filament CVD, microwave CVD has fewer contaminant issues. However, microwave CVD requires a high process pressure which can affect the film uniformity. Moreover, while microwave generated plasma created by microwave CVD hardware has relatively low ion energies, these generated ions can still attack the NCD grain boundary and induce grain structure disorder.
Therefore, there is a need for improved apparatus and methods for forming high quality diamond films.